Model of room-temperature resonant-tunneling current in metal/insulator and insulator/insulator heterostructures

摘要

Employing a multiband scattering formalism for ballistic tunneling currents, a systematic theoretical study of the current-voltage characteristics of metal-insulator and insulator-based resonant-tunneling diodes is presented. We predict ultrathin metal(CoSi2)/insulator( CaF2) and insulator( CdF2)/insulator( CaF2) heterostructures on silicon substrates to be excellent candidates for room-temperature quantum-effect devices. The scattering formalism in the framework of tight-binding theory is cast in a particularly compact and transparent form that is applicable to long-range tight-binding interactions and complex unit cells. The results are in good agreement with experimental data. The physical origin of the distinct current resonances, particularly in the metal/insulator structures, is explained in detail and found to originate in the localized character of the transition-metal d states. Furthermore, the stability of the resonance characteristics with regard to layer thickness variations, substrate orientations, and interface roughness is predicted. [References: 48]